The International Cessna^® 170 Association

How about some pros and cons on adding MMO or similar additives to fuel and/or oil? Recently an AP suggested I add some to oil and fuel.

Oh no you've opened up the MMO can of worms again.

Do a search on MMO and you'll find plenty for and against its use. I personally use it in my gas only and I believe it helps stop sticking valves.

And it smellls nice

n3437d wrote:How about some pros and cons on adding MMO or similar additives to fuel and/or oil? Recently an AP suggested I add some to oil and fuel.

Ask him to put some in there himself and log it into your logbooks.

(This'll get the log-in count up, Dale!)

George, that last replay was pretty slick

I always use MMO in the proper amount in my mogas as well as avgas when I can't find the good stuff on a long trip. Cheap insurance. I've never heard of anyone getting a stuck valve while using MMO, but plenty of them from folks not using MMO in the fuel. I've also been toying with the idea of using it in the oil just before oil change to dredge up the junk and wash it out. Minus side of this is that my engine has over 900 hours and don't know how much junk is inside the engine. Do I want this stuff breaking up and circulating around in the engine for the one hour before oil change? How much damage would this do VS just leaving in stuck in the nooks and crannies of the engine? I always use an engine flush in my auto engines, but have been doing so since I rebuilt them so I know that no gunk has been allowed to accumulate...nothing to break free and circulate around the engine.

Thoughts to ponder....

There's nothing wrong with a coating of varnish etc. on non-moving internal engine parts, ....in fact it's good. It prevents rust on those parts.
The parts that move against each other stay polished and lubed (with oil.)
Using solvents of any kind washes that protective coating off, sends the junk through the engine lubrication system, and does God-only-knows what to fine surfaces and bearings. If the "crud" is stuck to non-moving parts, ....leave it there where it can be a protective coating, is my position.

I agree George, but I still have a huge problem in South Africa with the lead in the 100LL fuel, it leads to a lot of valves sticking, my mechanic advised as you did never to use any non approved additve, AVBLEND is apparently I think a FAA/SAE approved additive, what is your idears about using it and what will you recommemnd with regards to sticky valves?
Regards
Ian

In my opinion, AvBlend is merely "approved" snake oil. The FAA will approve anything that they can be convinced doesn't immediately cause a direct problem. Don't ever believe that just because it's approved....that it's also good or that it actually performs as advertised. Approval does not impart that meaning.
Use TCP in your fuel to avoid lead problems, and change your oil often. I still change mine every 25 hours even tho' I have a spin on filter. Fifty hours isn't too bad, but don't EVER believe the filter people's claims that 100 hours between oil changes is OK. It's not. You cannot use automotive comparisions with validity because mogas doesn't contain lead.

Thanks for that George good gen, I change oil every 25 hours as well good to know I am not overdoing things, can you recommend any good spin on fliters?

What exactly is TCP?

Regards

Ian

I would be really curious John if you could give me the information regarding using MMO in the "proper amount". What is the proper amount? Where is the data stating what the proper amount is? What does the data say MMO will do?

Not trying to give you a hard time, just asking. I used MMO at one time myself with no ill (or known good) effects. I found a 4 gallon "set" @ Sams Club several yrs ago, bought it, & used almost a gallon in my auto fuel. Still have just over 3 gallons. Found the 3 full ones last weekend while digging though a shelf in my storage bldg! It works great on my airplane winch to keep it lubercated! Have not used it since and have not had any problems (known) while using that allfull 100LL. I think MMO is kind of like auto gas vs Avgas or Ford vs GM, etc.--whatever makes you feel warm & fuzzy.

N6888A

The proper amount I refer to is 4oz for each 10 gallons. Printed on the back of each beautiful red bottle of MMO. I got a bunch of reading material while up at AOPA EXPO recently, and saw that MMO was recommended in one of the engine care articles in the Cessna Owners Organization magazine. This is the first time I have seen MMO even mentioned outside of our little forum here. When I get a stuck valve while using auto fuel and MMO is the day I'll stop using it. Now I'll have to see about picking up some TCP for those long trips where I cannot find the good stuff and have to go with that leadball producing 100LL

I have been using Marvel Mystery Oil in the fuel since back in the 70's when they first started phasing out 80 octane fuel. In four airplanes during this time, I have never had a stuck valve. I believe in it for fuel, however I do not add it to the oil. I tried it once and it caused oil leaks to develope. The oil leak may have just been a concidence but I don't put it in the oil anyhow.

By the way George, whatever became of the pictures you took flying along the Outer Banks?

Harold H
Mbr #893